There are changes to the storage format in this release, so once you upgrade to 2.2.0 it will not be possible to downgrade. Due to a bug in storage, using 2.2.0 is not recommended.
There's various improvements to make administration easier. The alerts status page can show annotations, rules are better formatted, the runtime page includes more information, and flags, dropped targets and dropped alertmangers are now available from the API.
There have been performance improvements to federation and service discovery. Changes in bearer tokens no longer require reloading the configuration file. The
prometheus_sd_file_timestamp metric added in 2.1.0 now has the improved name
prometheus_sd_file_mtime_seconds. Additional metadata has been added to Azure SD.
There’s also a number of improvements, bug fixes and other changes, see the release notes for more detail.
Wondering when and how to upgrade to Prometheus 2.x? Contact us.